The anterior cruciate ligament is the most important ligamentous stabilizer of the knee, and disruption of this ligament can have devastating consequences. The ligament has a poor potential for healing and thus ligament replacement is often performed. The overall objective of our work is the design, development and study of a tissue engineered artificial ligament for use in anterior cruciate ligament reconstruction. We believe that a biological approach to ligament design--the combination of cells, factors and synthetic fibers--may lead to an adaptive living tissue. We envision an artificial graft in which degradable polymers are fabricated according to biomechanical requirements for the anterior cruciate ligament. These grafts will be seeded with fibroblast cells and loaded mechanically in vitro where the process of ligamentization will occur. At the appropriate time, the graft material will be implanted in vivo to reconstruct the anterior cruciate ligament. Under this grant, we propose to perform fundamental studies aimed at developing an understand understanding of the cellular parameters necessary to fabricate a neo-ligament for cruciate reconstruction. The aims of the project are to develop cultures of ligament-like fibroblast cells derived from the medial collateral ligament, anterior cruciate ligament, patellar tendon and Achilles tendon on of rabbits, and to determine their age-related kinetic and phenotypic changes when grown on tissue culture polystyrene and on candidate polymeric biomaterials for anterior cruciate replacement. Finally, under this grant, the effects of various growth factors on kinetics, and phenotypic expression of ligament-like cells will be studied.